Deep-rooted plant species recruit distinct bacterial communities in 3 m deep subsoil

Abstract

Deep-rooted plants can obtain water and nutrients from the subsurface, making them more resilient to climatic changes such as drought. In addition, the deeper root network also allow the plants to recruit bacteria from a larger reservoir in the soil. These bacteria might contribute to nutrient acquisition and provide other plant beneficial traits to the plant. However, the deep rhizosphere communities' compositions and their assembly dynamics are unknown. Here, we show, using three perennial crops, Kernza, lucerne and rosinweed, grown in 4 m RootTowers, that deep rhizosphere bacterial communities are plant specific, but clearly distinct from the shallow communities. We found that the diversity decreased with depth in the rhizosphere, whereas abundance of 16S rRNA gene copies did not change with depth in lucerne and rosinweed. Furthermore, we identified a subgroup (4-8%) of ASVs in the rhizosphere communities that could not be retrieved in the corresponding bulk soil communities. The abundances of genes determined by qPCR involved in N-cycling: amoA, nifH, nirK, nirS and nosZ differed significantly between plant species, suggesting differences in N content in the root exudates of the plant species. Our results suggest that colonization of the rhizosphere by bulk soil bacteria is not limited by carbon supply, but rather by dispersal. Furthermore, the abundance of N cycling genes indicate that deep rhizosphere bacteria have the potential to provide N through nitrogen fixation.

Bacterial Community Structure and Potential Microbial Coexistence Mechanism Associated with Three Halophytes Adapting to the Extremely Hypersaline Environment

“…On the one side, halophytes' microbiome may change the ion composition of soil around the root through microbial metabolism to further affect the adaptability against adversity such as hypersaline stress. On the other side, the root network also allows halophytes to recruit distinct bacteria from a larger soil microbial reservoir to construct microbiomes to benefit themselves [59]. Li et al confirmed the critical role of salt-induced root-derived bacteria (RDB) in enhancing plant adaptability to salt stress by measuring the composition and variation in the rhizosphere and endophyte bacteria of salt-sensitive (SS) and salt-resistant (SR) plants under soil conditions with or without salinity [60].…”